The present invention relates to an endoscope probe to be inserted into a body cavity to observe in vivo tissues (i.e., tissues of a living body) and an endoscope probe system including such an endoscope probe.
Conventionally, a confocal light scanning probe has been known, which scans a laser beam on tissues within a body cavity through a confocal optical system and receives the laser beam reflected by the tissues through the same confocal optical system to observe a precise surface image or tomogram of the tissues. An example of such a probe is disclosed in Japanese Patent Provisional Publication No. P2002-277743, for example.
Such a confocal light scanning probe selectively receives the laser beam reflected by the tissues at an object side focal plane of an objective lens of the confocal optical system by disposing a pin hole at an image side focal point of the objective lens, which pin hole allows only the light reflected at the object side focal plane to pass therethrough. The reflected light that has passed through the pin hole is then received by a light detector that generates an electrical signal representing the intensity of the reflected light.
To build up a two- or three-dimensional image of the tissues from the output of the light detector, the laser beam emitted from the confocal light scanning probe should be scanned on the target tissues. Therefore, the confocal light scanning probe is generally provided with a scanning mirror for scanning the laser beam on the tissue either two dimensionally or three dimensionally.
The confocal light scanning probe such as one disclosed in the Japanese Patent Application Provisional Publication No. P2002-277743 is provided with a scanning mirror, which is produced by etching a silicon substrate and is typically supported by torsion bars which are produced by etching integrally with the mirror portion. The scanning mirror is generally actuated by an electrostatic force to rotatably vibrate by twisting the torsion bars.
It should be noted that the scanning mirror arranged as above can precisely control the vibrating amplitude of the mirror since it is actuated by a electrostatic force. However, since the required driving voltage of the entire system is quite high, e.g. a few hundreds volts, a leakage current may occur when the confocal light scanning probe is inserted into a body cavity.
Further, the torsion bars supporting the mirror may break when they are twisted by an excessively large force (i.e. when the laser beam scanning range is too large), or for a large number of times (i.e. when the laser beam scanning is carried out for a long time).
Further, the conventional confocal light scanning probe requires a finite duration of time for scanning an area on the tissue to be observed using a beam. Therefore, it is difficult to achieve real time observation of the tissue by using the confocal light scanning probe.